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244. Explain fig. 60. What is the length of the small intestine, and how is it divided? What is the length of the large intestine? Give its divisions. 245. Describe the duodenum.
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246. The JEJUNUM is continuous with the duodenum. It is thicker than the rest of the small intestine, and has a pinkish tinge.
247. The ILEUM is smaller, and thinner in texture, and somewhat paler, than the jejunum. There is no mark to distinguish the termination of the one or the commencement of the other. The ileum terminates near the right haunch-bone, by a valvular opening into the colon at an obtuse angle. This arrangement prevents the passing of substances from the colon into the ileum. The jejunum and ileum are surrounded above and at the sides by the colon.
248. The small intestine, like the stomach, has three coats. The inner, or mucous coat is thrown into folds, or valves. In consequence of this valvular arrangement, the mucous membrane is more extensive than the other tissues, and gives a greater extent of surface with which the aliment comes in contact. There are imbedded under this membrane an immense number of minute glands, and it has a great number of piles, like those upon velvet. For this reason, this membrane is sometimes called the vil'lous coat.
249. The CAECUM is the blind pouch, or cul-de-sac, at the commencement of the large intestine. Attached to its extremity is the ap-pend'ix verm-i-form'is, (a long, worm-shaped tube.) It is from one to six inches in length, and of the size of a goose-quill.
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What important ducts open into it? 246. Describe the jejunum. 247. The ileum. 248. What is said of the coats of the intestines? Why is the mucous membrane sometimes called the villous coat? 249. Describe the caecum.
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250. The COLON is divided into three parts—the ascending, transverse, and descending. The ascending colon passes upward from the right haunch-bone to the under surface of the liver. It then bends inward, and crosses the upper part of the abdomen, below the liver and stomach, to the left side under the name of the transverse colon. At the left side, it turns, and descends to the left haunch-bone, and is called the descending colon. Here it makes a peculiar curve upon itself, which is called the sig'moid flex'ure.
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250. Describe the course of the divisions of the colon. Explain fig. 61.
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251. The RECTUM is the termination of the large intestine. The large intestine has three coats, like the stomach and small intestine. The longitudinal fibres of the muscular coat are collected into three bands. These bands are nearly one half shorter than the intestine, and give it a sacculated appearance, which is characteristic of the caecum and colon.
252. The LACTEALS are minute vessels, which commence in the villi, upon the mucous surface of the small intestine. From the intestine they pass between the membranes of the mes'en-ter-y to small glands, which they enter. The first range of glands collects many small vessels, and transmits a few larger branches to a second range of glands; and, finally, after passing through several successive ranges of these glandular bodies, the lacteals, diminished in number and increased in size, proceed to the enlarged portion of the thoracic duct, into which they open. They are most numerous in the upper portion of the small intestine.
253. The THORACIC DUCT commences in the abdomen, by a considerable dilatation, which is situated in front of the lower portion of the spinal column. From this point, it passes through the diaphragm, and ascends to the lower part of the neck. In its ascent, it lies anterior to the spine, and by the side of the aorta and oesophagus. At the lower part of the neck, it makes a sudden turn downward and forward, and terminates by opening into a large vein which passes to the heart. The thoracic duct is equal in diameter to a goose-quill, and, at its termination, is provided with a pair of semilunar valves, which prevent the admission of venous blood into its cylinder.
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251. What is said of the arrangement of the fibres of the muscular coat of the large intestine? 252. What are the lacteals? Give their course from the mucous coat of the intestine to the thoracic duct. 253. Describe the course of the thoracic duct. How is the venous blood prevented from passing into this duct?
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Explain fig. 62. What is said respecting the mesenteric glands?
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Observation. The mesenteric glands, which are situated between two layers of serous membrane (mesentery) that connects the small intestine with the spinal column, occasionally become diseased in childhood, and prevent the chyle from passing to the thoracic duct. Children thus affected have a voracious appetite, and at the same time are becoming more and more emaciated. The disease is called mesenteric consumption.
254. The LIVER, a gland appended to the alimentary canal, is the largest organ in the system, and weighs about four pounds. It is situated in the right side, below the diaphragm, and is composed of several lobes. Its upper surface is convex; its under, concave. This organ is retained in its place by several ligaments. It performs the double office of separating impurities from the venous blood, and of secreting a fluid (bile) necessary to chylification. On the under surface of the liver is a membranous sac, called the gall-cyst, which is generally considered as a reservoir for the bile.
Observation. A good idea of the liver and intestines can be obtained by examining these parts of a pig. In this animal, the sacs, or pouches, of the large intestine are well defined.
255. The PANCREAS is a long, flattened gland, analogous to the salivary glands. It is about six inches in length, weighs three or four ounces, and is situated transversely across the posterior wall of the abdomen, behind the stomach. A duct from this organ opens into the duodenum.
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254. Describe the liver. 255. What is said of the pancreas?
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256. The SPLEEN, (milt,) so called because the ancients supposed it to be the seat of melancholy, is an oblong, flattened organ, situated in the left side, in contact with the diaphragm, stomach, and the pancreas. It is of a dark, bluish color, and is abundantly supplied with blood, but has no duct which serves as an outlet for any secretion. Its use is not well determined.
257. The OMENTUM (caul) consists of four layers of the serous membrane, which descends from the stomach and transverse colon. A quantity of adipose matter is deposited around its vessels, which ramify through its structure. Its function is twofold in the animal economy. 1st. It protects the intestines from cold. 2d. It facilitates the movements of the intestines upon each other during their vermicular, or worm-like action.
258. Every part of the digestive apparatus is supplied with arteries, veins, lymphatics, and nervous filaments, from the ganglionic system of nerves.
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256. Why is the spleen so called? What is peculiar to this organ? 257. Of what is the omentum composed? What is its use? 258. With what is every part of the digestive apparatus supplied?
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CHAPTER XIV.
PHYSIOLOGY OF THE DIGESTIVE ORGANS.
259. Substances received into the stomach as food, must necessarily undergo many changes before they are fitted to form part of the animal body. The solid portions are reduced to a fluid state, and those parts that will nourish the body are separated from the waste material.
260. The first preparation of food for admission into the system, consists in its proper mastication. The lips in front, the cheeks upon the side, the soft palate, by closing down upon the base of the tongue, retain the food in the mouth, while it is subjected to the; process of mas-ti-ca'tion, (chewing.) The tongue rolls the mass around, and keeps it between the teeth, while they divide the food to a fineness suitable for the stomach.
261. While the food is in process of mastication, there is incorporated with it a considerable amount of sa-li'va, (spittle.) This fluid is furnished by the salivary glands, situated in the vicinity of the mouth. The saliva moistens and softens the food, so that, when carried into the pharynx. it is passed, with ease, through the oesophagus into the stomach.
262. When the food has been properly masticated, (and in rapid eaters when it is not,) the soft palate is raised from the base of the tongue backward, so as to close the posterior opening through the nostrils. By a movement of the muscles of the tongue, cheeks, and floor of the mouth, simultaneous with that of the soft palate, the food is pressed into the upper part of the pharynx.
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259-272. Give the physiology of the digestive organs. 259. What is necessary before food can nourish the body? 260. Describe how mastication is performed. 261. Of what use is the saliva in the process of mastication? 262. How is the food pressed into the pharynx?
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263. When in the pharynx, the food and drink are prevented from passing into the trachea by a simple valve-like arrangement, called the ep-i-glot'tis. The ordinary position of this little organ is perpendicular, so as not to obstruct the passage of air into the lungs; but in the act of swallowing, it is brought directly over the opening of the trachea, called the glot'tis. The food, being forced backward, passes rapidly over the epiglottis into the oesophagus, where the circular band of muscular fibres above, contracts and forces the food to the next lower band. Each band relaxes and contracts successively, and thus presses the alimentary ball downward and onward to the stomach.[8]
[8] The process of deglutition may be comprehended by analyzing the operation of swallowing food or saliva.
Observation. If air is inhaled when the food or drink is passing over the glottis, some portions of it may be carried into the larynx or trachea. This produces violent spasmodic coughing, and most generally occurs when an attempt is made to speak while masticating food; therefore, never talk when the mouth contains food.
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263. When the food is in the pharynx, how is it prevented from passing into the trachea, or windpipe? Describe how it is passed into the stomach? Give the observation. 264. Describe how the food in the stomach is converted into chyme.
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264. When the food reaches the stomach, the gastric glands are excited to action, and they secrete a powerful solvent, called gastric juice. The presence of food in the stomach also increases a contractile action of the muscular coat, by which the position of the food is changed from one part of this cavity to another. Thus the aliment is brought in contact with the mucous membrane, and each portion of it becomes saturated with gastric juice, by which it is softened, or dissolved into a pulpy homogeneous mass, of a creamy consistence, called Chyme. The food is not all converted into chyme at the same time; but as fast as it is changed, it passes through the pyloric orifice into the duodenum.
Observation. The gastric juice has the property of coagulating liquid albuminous matter when mixed with it. It is this property of rennet, which is an infusion of the fourth stomach of the calf, by which milk is coagulated, or formed into "curd."
265. The CHYME is conveyed through the pyloric orifice of the stomach into the duodenum. The chyme not only excites an action in the duodenum, but also in the liver and pancreas. Mucus is then secreted by the duodenum, bile by the liver, and pancreatic fluid by the pancreas. The bile and pancreatic fluid are conveyed into the duodenum, and mixed with the chyme. By the action of these different fluids, the chyme is converted into a fluid of a whitish color, called Chyle, and into residuum.
Observation. The bile has no agency in the change through which the food passes in the stomach. In a healthy condition of this organ, no bile is found in it. The common belief, that the stomach has a redundancy of this secretion, is erroneous. If bile is ejected in vomiting, it merely shows, not only that the action of the stomach is inverted, but also that of the duodenum. A powerful emetic will, in this way, generally bring this fluid from the most healthy stomach. A knowledge of this fact might save many a stomach from the evils of emetics, administered on false impressions of their necessity, and continued from the corroboration of these by the appearance of bile, till derangement, and perhaps permanent disease, are the consequences.
266. The CHYLE and residual matter are moved over the mucous surface of the small intestine, by the action of its muscular coat. As the chyle is carried along the tract of the intestine, it comes in contact with the villi, where the lacteal vessels commence. These imbibe, or take up, the chyle, and transfer it through the mesenteric glands into the thoracic duct, through which it is conveyed into a large vein at the lower part of the neck. In this vein the chyle is mixed with the venous fluid. The residual matter is conveyed into the large intestine, through which it is carried and excreted from the system. (Appendix E.)
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What peculiar property has gastric juice? 265. Where and how is chyme converted into chyle? What is said in regard to the bile? 266. What becomes of the chyle? Of the residuum?
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267. In the process of digestion, the food is subjected to five different changes. 1st. The chewing and admixture of the saliva with the food; this process is called mastication.
268. 2d. The change through which the food passes in the stomach by its muscular contraction, and the secretion from the gastric glands; this is called chymification.
269. 3d. The conversion of the homogeneous chyme, by the agency of the bile and pancreatic secretions, into a fluid of milk-like appearance; this is chylification.
270. 4th. The absorption of the chyle by the lacteals, and its transfer through them and the thoracic duct, into the subclavian vein at the lower part of the neck.[9]
[9] The chyle is changed by the lacteals and mesenteric glands, but the nature of this change is not, as yet, well defined or understood.
271. 5th. The separation and excretion of the residuum.
272. Perfection of the second process of digestion requires thorough and slow mastication. The formation of proper chyle demands appropriate mastication and chymification; while a healthy action of the lacteals requires that all the anterior stages of the digestive process be as perfect as possible. (Appendix F.)
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267. Recapitulate the five changes in the digestive process.
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Note. Let the pupil review the anatomy and physiology of the digestive organs from figs. 62 and 65, or from anatomical outline plate No. 5.
CHAPTER XV.
HYGIENE OF THE DIGESTIVE ORGANS.
273. It is a law of the system, that each organ is excited to healthy and efficient action, when influenced by its appropriate stimulus. Accordingly, nutrient food, that is adapted to the wants of the system, imparts a healthy stimulation to the salivary glands during the process of mastication. The food that is well masticated, and has blended with it a proper amount of saliva, will induce a healthy action in the stomach. Well-prepared chyme is the natural stimulus of the duodenum, liver, and pancreas; pure chyle is the appropriate excitant of the lacteal vessels.
274. The perfection of the digestive process, as well as the health of the general system, requires the observance of certain conditions. These will be considered under four heads:—1st. The Quantity of food that should be taken. 2d. Its Quality. 3d. The Manner in which it should be taken. 4th. The Condition of the system when food is taken.
275. The QUANTITY of food necessary for the system varies. Age, occupation, temperament, temperature, habits, amount of clothing, health and disease are among the circumstances which produce the variation.
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273-330. Give the hygiene of the digestive organs. 273. Give a law of the system. What is the appropriate stimulus of the salivary glands during mastication? Of the stomach? Of the duodenum? Of the lacteal vessels? 274. What does the perfection of the digestive organs require? 275. What exert an influence on the quantity of food necessary for the system?
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276. The child and youth require food to promote the growth of the different parts of the body. The more rapid the growth of the child, the greater the demand for food. This accounts for the keen appetite and vigorous digestion in childhood. When the youth has attained his full growth, this necessity for nutriment ceases; after this period of life, if the same amount of food is taken, and there is no increase of labor or exertion, the digestive apparatus will become diseased, and the vigor of the whole system diminished.
Observation. When the body has become emaciated from want of nutriment, either from famine or disease, there is an increased demand for food. This may be gratified with impunity until the individual has regained the usual size, but repletion should be avoided.
277. Food is required to repair the waste, or loss of substance that attends action. In every department of nature, waste, or loss of substance, attends and follows action. When an individual increases his exercise,—changes from light to severe labor,—or the inactive and sedentary undertake journeys for pleasure, the fluids of the system circulate with increased energy. The old and exhausted particles of matter are more rapidly removed through the action of the vessels of the skin, lungs, kidneys, and other organs, and their places are filled with new atoms, deposited by the small blood-vessels.
278. As the chyle supplies the blood with the newly vitalized particles of matter, there is, consequently, an increased demand for food. This want of the system induces, in general, a sensation of hunger or appetite, which may be regarded as an indication of the general state of the body. The sympathy that exists throughout the system accords to the stomach the power of making known this state to the nervous system, and, if the functions of this faithful monitor have not been impaired by disease, abuse, or habit, the call is imperious, and should be regarded.
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276. At what age is the appetite keen and the digestion vigorous? Why? What is said in regard to the quantity of food when the youth has attained his growth? What exception, as given in the observation? 277. Give another demand for food. What effect has increased exercise upon the system? 278. How are the new particles of matter supplied? What does this induce?
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279. When exercise or labor is lessened, the quantity of food should be diminished. When a person who has been accustomed to active exercise, or even hard manual labor, suddenly changes to an employment that demands less activity, the waste attendant on action will be diminished in a corresponding degree; hence the quantity of food should be lessened in nearly the same proportion as the amount of exercise is diminished. If this principle be disregarded, the tone of the digestive organs will be impaired, and the health of the system enfeebled.
280. This remark is applicable to those students who have left laborious employments to attend school. Although the health is firm, and the appetite keen from habit, yet every pupil should practise some self-denial, and not eat as much as the appetite craves, the first week of the session. After some days, the real wants of the system will generally be manifested by a corresponding sensation of hunger.
Observation. It is a common observation that in academies and colleges, the older students from the country, who have been accustomed to hard manual labor, suffer more frequently from defective digestion and impaired health than the younger and feebler students from the larger towns and cities.
281. Food is essential in maintaining a proper temperature of the system. The heat of the system, at least in part, is produced in the minute vessels of the several organs, by the union of oxygen with carbon and hydrogen, which the food and drink contain. The amount of heat generated, is greatest when it is most rapidly removed from the system, which occurs in cold weather. This is the cause of the system requiring more food in winter than summer.
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279. Why should the quantity of food be diminished when the exercise is lessened? What effect if this principle be disregarded? 280. To what class is this remark applicable? What is often observed among students in academies and colleges? 281. State another demand for food. What is one source of heat in the body?
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Observation. Persons that do not have food sufficient for the natural wants of the system, require more clothing than those who are well fed.
282. The last-mentioned principle plainly indicates the propriety and necessity of lessening the quantity of food as the warm season approaches. Were this practised, the tone of the stomach and the vigor of the system would continue unimpaired, the "season complaints" would be avoided, and the "strengthening bitters" would not be sought to create an appetite.
Observation. Stable-keepers and herdsmen are aware of the fact, that as the warm season commences, then animals require less food. Instinct teaches these animals more truly, in this particular, than man allows reason to guide him.
283. The quantity of food should have reference to the present condition of the digestive organs. If they are weakened or diseased, so that but a small quantity of food can be properly digested or changed, that amount only should be taken. Food does not invigorate the system, except it is changed, as has been described in previous paragraphs.
Observation. When taking care of a sick child, the anxiety of the mother and the sufferings of the child may induce her to give food when it would be highly injurious. The attending physician is the only proper person to direct what quantity should be given.
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Why do we eat more in the winter than in the summer? What practical observation is given? 282. Why should the quantity of food be lessened as warm weather commences? What would be avoided if this principle were obeyed? 283. Why should the present condition of the digestive organs be regarded in reference to the quantity of food? Mention an instance in which it would be injudicious to give food.
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284. The quantity of food is modified, in some degree, by habit. A healthy person, whose exercise is in pure air, may be accustomed to take more food than is necessary. The useless excess is removed from the system by the waste outlets, as the skin, lungs, liver, kidneys, &c. In such cases, if food is not taken in the usual quantity, there will be a feeling of emptiness, if not of hunger, from the want of the usual distention of the stomach. This condition of the digestive organs may be the result of disease, but it is more frequently produced by inordinate daily indulgence in eating, amounting almost to gluttony.
285. Large quantities of food oppress the stomach, and cause general languor of the whole body. This is produced by the extra demands made on the system for an increased supply of blood and nervous fluid to enable the stomach to free itself of its burden. Thus, when we intend to make any extraordinary effort, mental or physical, at least for one meal, we should eat less food than usual, rather than a greater quantity.
286. No more food should be eaten than is barely sufficient to satisfy the appetite. Nor should appetite be confounded with taste. The one is a natural desire for food to supply the wants of the system; the other is an artificial desire merely to gratify the palate.
287. Although many things may aid us in determining the quantity of food proper for an individual, yet there is no certain guide in all cases. It is maintained by some, that the sensation of hunger or appetite is always an indication of the want of food, while the absence of this peculiar sensation is regarded as conclusive evidence that aliment is not demanded. This assertion is not correct, as an appetite may be created for food by condiments and gormandizing, which is as artificial and as morbid as that which craves tobacco or ardent spirits. On the other hand, a structural or functional disease of the brain may prevent that organ from taking cognizance of the sensations of the stomach, when the system actually requires nourishment. Observation shows, that disease, habit, the state of the mind, and other circumstances, exert an influence on the appetite.
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284. Show the effect of habit upon the quantity of food that is eaten. What is said in regard to inordinate eating? 285. What is the effect of eating large quantities of food? What suggestion when an extraordinary effort, either mental or physical, is to be made? 286. How much food should generally be eaten? 287. What is the assertion of some persons relative to the quantity of food necessary for the system?
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Observation. Dr. Beaumont noticed, in the experiments upon Alexis St. Martin, that after a certain amount of food was converted into chyme, the gastric juice ceased to ooze from the coats of the stomach. Consequently, it has been inferred by some writers on physiology, that the glands which supply the gastric fluid, by a species of instinctive intelligence, would only secrete enough fluid to convert into chyme the aliment needed to supply the real wants of the system. What are the reasons for this inference? There is no evidence that the gastric glands possess instinctive intelligence, and can there be a reason adduced, why they may not be stimulated to extra functional action as well as other organs, and why they may not also be influenced by habit?
288. While all agree that the remote or predisposing cause of hunger is, usually, a demand of the system for nutrient material, the proximate or immediate cause of the sensation of hunger is not clearly understood. Some physiologists suppose that it is produced by an engorged condition of the glands of the stomach which supply the gastric juice; while others maintain that it depends on a peculiar condition of the nervous system.
289. The QUALITY of the food best adapted to the wants of the system is modified by many circumstances. There are many varieties of food, and these are much modified by the different methods of preparation. The same kind of food is not equally well adapted to different individuals, or to the same individual in all conditions; as vocation, health, exposure, habits of life, season, climate, &c., influence the condition of the system.
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What does observation show? 288. What is said of the causes of hunger? 289. Why is not the same kind of food adapted to different individuals?
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290. All articles of food may be considered in two relations: 1st, As nutritive. 2d, As digestible. Substances are nutritious in proportion to their capacity to yield the elements of chyle, of which carbon, oxygen, hydrogen, and nitrogen are the most essential; they are digestible in proportion to the facility with which they are acted upon by the gastric juice. These properties should not be confounded in the various articles used for food.
291. As a "living body has no power of forming elements, or of converting one elementary substance into another, it therefore follows that the elements of which the body of an animal is composed must be in the food." (Chap. III.) Of the essential constituents of the human body, carbon, hydrogen, oxygen, and nitrogen are the most important, because they compose the principal part of the animal body; while the other elements are found in very small proportions, and many of them only in a few organs of the system. (Appendix G.)
Observation. Nitrogen renders food more stimulating, particularly if combined with a large quantity of carbon, as beef. Those articles that contain the greatest amount of the constituent elements of the system are most nutritious. As milk and eggs contain all the essential elements of the human system, so they are adapted to almost universal use, and are highly nutritious.
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290. In what proportion are substances nutritious? Digestible? Why does beef stimulate the system? What is said of milk and eggs?
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292. The following table, by Pereira, in his treatise on Food and Diet may aid the student in approximating to correct conclusions of the quantity of nutriment in different kinds of food, and its adaptation to the wants of the system.
TABLE,
SHOWING THE AVERAGE QUANTITY OF DRY, OR SOLID MATTER, CARBON, NITROGEN, AND MOISTURE, IN DIFFERENT ARTICLES OF DIET.
- - - - One hundred Parts. Dry Carbon. Nitrogen. Water Matter. - - - - Arrowroot, 81.8 36.4 18.2 Beans, 85.89 38.24 14.11 Beef, fresh, 25 12.957 3.752 75 Bread, rye, 67.79 30.674 32.21 Butter, 100 65.6 Cabbage, 7.7 0.28 92.3 Carrot, 12.4 0.30 87.6 Cherries, 25.15 74.85 Chickens, 22.7 77.3 Codfish, 20 80 Cucumbers, 2.86 97.14 Eggs, whites, 20 80 , yolk, 46.23 53.77 Lard, hog's, 100 79.098 Milk, cow's, 12.98 87.02 Oats, 79.2 40.154 1.742 20.8 Oatmeal, 93.4 6.6 Olive-oil, 100 77.50 Oysters, 12.6 87.4 Peaches, 19.76 80.24 Pears, 16.12 83.88 Peas, 84 35.743 16 Plums, greengage, 28.90 71.10 Potatoes, 24.1 10.604 0.3615 75.9 Rye, 83.4 38.530 1.417 16.6 Suet, mutton, 100 78.996 Starch, potato, 82 36.44 18 , wheat, 85.2 37.5 14.8 Sugar, maple, 42.1 , refined, 42.5 , brown, 40.88 Turnips, 7.5 3.2175 0.1275 92.5 Veal, roasted, 52.52 14.70 Wheat, 85.5 39.415 1.966 14.5 - - - -
Note. Let the pupil mention those articles of food that are most nutritious, from a review of this table, and the last four paragraphs.
293. Those articles that do not contain the essential elements of the system should not be used as exclusive articles of diet. This principle has been, and may be illustrated by experiment. Feed a dog with pure sugar, or olive-oil, (articles that contain no nitrogen,) for several weeks, and the evil effects of non-nitrogenous nutriment will be manifested. At first, the dog will take his food with avidity, and seem to thrive upon it; soon this desire for food will diminish, his body emaciate, his eye become ulcerated, and in a few weeks he will die; but mix bran or sawdust with the sugar or oil, and the health and vigor of the animal will be maintained for months. A similar phenomenon will be manifested, if grain only be given to a horse, without hay, straw, or material of like character. (Appendix H.)
294. Some articles of food contain the elements of chyle in great abundance, yet afford but little nutriment, because they are difficult of digestion; while other articles contain but a small quantity of these elements, and afford more nourishment, because they are more easily affected by the digestive process.
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293. How has the effect of non-nitrogenous nutriment been illustrated? 294. Why do some articles of food that contain the elements of chyle afford but little nutriment? Why do articles that contain a small quantity of these elements afford more nourishment? 295. How was the time required for digesting different articles of food ascertained?
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295. The following table exhibits the general results of experiments made on Alexis St. Martin, by Dr. Beaumont, when he endeavored to ascertain the time required for the digestion of different articles of food.[10] The stomach of St. Martin was ruptured by the bursting of a gun. When he recovered from the effects of the accident under the surgical care of Dr. Beaumont, the stomach became adherent to the side, with an external aperture. Nature had formed a kind of valve, which closed the aperture from the interior, and thus prevented the contents of the stomach from escaping; but on pushing it aside, the process of digestion could be seen. Through this opening, the appearance of the coats of the stomach and food, at different stages of digestion, were examined.
[10] The time required for the digestion of the different articles of food might vary in other persons; and would probably vary in the same individual at different periods, as the employment, health, season, &c., exert a modifying influence.
TABLE,
SHOWING THE MEAN TIME OF DIGESTION OF THE DIFFERENT ARTICLES OF DIET.
- Articles. Preparation. Time h. m. - Apples, sour, hard, Raw, 2 50 Apples, sour, mellow, Raw, 2 Apples, sweet, do., Raw, 1 30 Bass, striped, fresh, Broiled, 3 Beans, pod, Boiled, 2 30 Beef, fresh, lean, rare, Roasted, 3 Beef, fresh, lean, dry, Roasted, 3 30 Beef steak, Broiled, 3 Beef, with salt only, Boiled, 3 36 Beef, with mustard, Boiled, 3 10 Beef, fresh, lean, Fried, 4 Beef, old, hard, salted, Boiled, 4 15 Beets, Boiled, 3 45 Bread, wheat, fresh, Baked, 3 30 Bread, corn, Baked, 3 15 Butter, Melted, 3 30 Cabbage head, Raw, 2 30 Cabbage, with vinegar, Raw, 2 Cabbage, Boiled, 4 30 Cake, sponge, Baked, 2 30 Carrot, orange, Boiled, 3 15 Catfish, Fried, 3 30 Cheese, old, strong, Raw, 3 30 Chicken, full-grown, Fricas'd, 2 45 Codfish, cured, dry, Boiled, 2 Corn, green, & beans, Boiled, 3 45 Corn bread, Baked, 3 15 Corn cake, Baked, 3 Custard, Baked, 2 45 Dumpling, apple, Boiled, 3 Ducks, domesticated, Roasted, 4 Ducks, wild, Roasted, 4 30 Eggs, fresh, Boiled hard, 3 30 Eggs, fresh, Boiled soft, 3 Eggs, fresh, Fried, 3 30 Eggs, fresh, Raw, 2 Flounder, fresh, Fried, 3 30 Fowl, domestic, Boiled, 4 Fowl, domestic, Roasted, 4 Goose, Roasted, 2 30 Lamb, fresh, Broiled, 2 30 Liver, beef's, fresh, Broiled, 2 Meat hashed with vegetables, Warm'd, 2 30 Milk, Boiled, 2 Milk, Raw, 2 15 Mutton, fresh, Roasted, 3 15 Mutton, fresh, Broiled, 3 Mutton, fresh, Boiled, 3 Oysters, fresh, Raw, 2 55 Oysters, fresh, Roasted, 3 15 Oysters, fresh, Stewed, 3 30 Parsnips, Boiled, 2 30 Pig, sucking, Roasted, 2 30 Pigs' feet, soused, Boiled, 1 Pork, fat and lean, Roasted, 5 15 Pork, recently salted, Boiled, 4 30 Pork, recently salted, Fried, 4 15 Pork, recently salted, Broiled, 3 15 Pork, recently salted, Raw, 3 Pork, steak, Broiled, 3 15 Potatoes, Irish, Boiled, 3 30 Potatoes, Irish, Baked, 2 30 Rice, Boiled, 1 Sago, Boiled, 1 45 Salmon, salted, Boiled, 4 Sausage, fresh, Broiled, 3 20 Soup, beef, vegetables, and Boiled, 4 bread, Soup, chicken, Boiled, 3 Soup, mutton, Boiled, 3 30 Soup, oyster, Boiled, 3 30 Suet, beef, fresh, Boiled, 5 30 Suet, mutton, Boiled, 4 30 Tapioca, Boiled, 2 Tripe, soused, Boiled, 1 Trout, salmon, fresh, Boiled, 1 30 Trout, salmon, fresh, Fried, 1 30 Turkey, domesticated, Roasted, 2 30 Turkey, Boiled, 2 25 Turkey, wild, Roasted, 2 18 Turnips, flat, Boiled, 3 30 Veal, fresh, Broiled, 4 Veal, fresh, Fried, 4 30 Venison steak, Broiled, 1 35 -
296. In view of this table, the question may be suggested, Is that article of food most appropriate to the system which is most easily and speedily digested? To this it may be replied, that the stomach is subject to the same law as the muscles and other organs; exercise, within certain limits, strengthens it. If, therefore, we always eat those articles most easily digested, the digestive powers will be weakened; if over-worked, they will be exhausted. Hence the kind and amount of food should be adapted to the maintenance of the digestive powers, and to their gradual invigoration when debilitated.
Observation. Food that is most easily digested is not always most appropriate to a person convalescing from disease. If the substance passes rapidly through the digestive process, it may induce a recurrence of the disease. Thus the simple preparations which are not stimulating, as water-gruel, are better for a sick person than the more digestible beef and fish.
297. The question is not well settled, whether animal or vegetable food is best adapted to nourish man. There are nations, particularly in the torrid zone, that subsist, exclusively, on vegetables; while those of the frigid zone feed on fish or animal food. In the temperate zone, among civilized nations, a mixed diet is almost universal. When we consider the organization of the human system, the form and arrangement of the teeth, the structure of the stomach and intestines, we are led to conclude, that both animal and vegetable food is requisite, and that a mixed diet is most conducive to strength, health, and long life.
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296. How is the question answered, whether that article is most appropriate to the system which is most easily digested? Give observation. 297. What is said of the adaptation of animal and vegetable food to man?
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298. The food should be adapted to the distensible character of the stomach and alimentary canal. The former will be full, if it contain only a gill; it may be so distended as to contain a quart. The same is true of the intestines. If the food is concentrated, or contains the quantity of nutriment which the system requires, in small bulk, the stomach and intestines will need the stimulation of distention and friction, which is consequent upon the introduction and transit of the innutritious material into and through the alimentary canal. If the food is deficient in innutritious matter, the tendency is, to produce an inactive and diseased condition of the digestive organs. For this reason, nutrient food should have blended with it innutritious material. Unbolted wheat bread is more healthy than hot flour cakes; ripe fruits and vegetables than rich pies, or jellies.
Observation. 1st. The observance of this rule is of more importance to students, sedentary mechanics, and those individuals whose digestive apparatus has been enfeebled, than to those of active habits and firm health.
2d. The circumstance that different articles of food contain different proportions of waste, or innutritious matter, may be made practically subservient in the following way: If, at any particular season of the year, there is a tendency to a diarrhoea, an article that contains a small proportion of waste should be selected for food; but, if there is a tendency to an inactive or costive condition of the intestinal canal, such kinds of food should be used as contain the greatest proportion of waste, as such articles are most stimulating to the digestive organs, and, consequently, most laxative.
299. In the selection of food, the influence of season and climate should be considered. Food of a highly stimulating character may be used almost with impunity during the cold weather of a cold climate; but in the warm season, and in a warm climate, it would be very deleterious. Animal food, being more stimulating than vegetable, can be eaten in the winter but vegetable food should be used more freely in the spring and summer.
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298. What is said of the distensible character of the stomach and alimentary canal? What is the effect of eating highly concentrated food? Why is the unbolted wheat bread more healthy than flour cakes? Give observation 1st. Observation 2d. 299. What kind of food is adapted to cold weather? To warm weather?
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300. The influence of food on the system is modified by the age of the individual. The organs of a child are more sensitive and excitable than those of a person advanced in years. Therefore a vegetable diet would be most appropriate for a child, while stimulating animal food might be conducive to the health of a person advanced in life.
Observation. When the digestive organs are highly impressible or diseased, it is very important to adopt a nutritious, unstimulating, vegetable diet, as soon as the warm season commences.
301. Habit is another strong modifying influence. If a person has been accustomed to an animal or vegetable diet, and there is a sudden change from one to the other, a diseased condition of the system, particularly of the digestive apparatus, usually follows. When it is necessary to change our manner of living, it should be done gradually.[11]
[11] The system is gradually developed, and all changes of food, apparel, labor, exercise, or position, should be gradual. Even a change from a bad to a good habit, on this principle, should be gradual.
302. Some temperaments require more stimulating food than others. As a general rule, those persons whose sensations are comparatively obtuse, and movements slow, will be benefited by animal food; while those individuals whose constitutions are highly impressible, and whose movements are quick and hurried, require a nutritious and unstimulating vegetable diet.
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300. What kinds of food are appropriate to old age? Why? What kinds to childhood? Why? 301. What is the effect when there is a sudden change from a vegetable to an animal diet? How should all changes of the system be made? 302. Do different temperaments require different kinds of food? What general rule is given?
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CHAPTER XVI.
HYGIENE OF THE DIGESTIVE ORGANS, CONTINUED.
303. The MANNER in which food should be taken is of much practical importance; upon it the health of the digestive organs measurably depends. But few circumstances modify the proper manner of taking food, or should exercise any controlling influence.
304. Food should be taken at regular periods. The interval between meals should be regulated by the character of the food, the age, health, exercise, and habits of the individual. The digestive process is more energetic and rapid in the young, active, and vigorous, than in the aged, indolent, and feeble; consequently, food should be taken more frequently by the former than by the latter class.
305. In some young and vigorous persons, food may be digested in one hour; in other persons, it may require four hours or more. The average time, however, to digest an ordinary meal, will be from two to four hours. In all instances, the stomach will require from one to three hours to recruit its exhausted powers after the labor of digesting a meal before it will again enter upon the vigorous performance of its duties.
306. Food should not be taken too frequently. If food is taken before the stomach has regained its tone and energy by repose, the secretion of the gastric juice, and the contraction of the muscular fibres, will be imperfect. Again, if food is taken before the digestion of the preceding meal has been completed, the effects will be still worse, because the food partially digested becomes mixed with that last taken. Therefore the interval between each meal should be long enough for the whole quantity to be digested, and the time of repose should be sufficient to recruit the exhausted organs. The feebler the person and the more debilitated the stomach, the more important to observe the above directions.
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303. Why is it important that we regard the manner of taking our food? 304. How should the intervals between meals be regulated? 305. What is the average time required to digest an ordinary meal? 306. Why should not food be taken too frequently?
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Observation. In the feeding of infants, as well as in supplying food to older children, the preceding suggestions should always be regarded. The person who has been confined by an exhausting sickness, should most scrupulously regard this rule, if he wishes to regain his strength and flesh with rapidity. As the rapidity of the digestive process is less in students and individuals who are engaged in sedentary employments, than in stirring agriculturists, the former class are more liable to take food too frequently than the latter, while its observance is of greater importance to the sedentary artisan than to the lively lad and active farmer.
307. Food should be well masticated. All solid aliments should be reduced to a state of comparative fineness, by the teeth, before it is swallowed; the gastric fluid of the stomach will then blend with it more readily, and act more vigorously in reducing it to chyme. The practice of swallowing solid food, slightly masticated, or "bolting" it down, tends to derange the digestive process and impair the nutrition of the system.
308. Mastication should be moderate, not rapid. In masticating food, the salivary glands are excited to action, and some time must elapse before they can, secrete saliva in sufficient quantities to moisten it. If the aliment is not supplied with saliva, digestion is retarded; besides, in rapid eating, more food is generally consumed than the system demands, or can be easily digested. Laborers, as well as men of leisure, should have ample time for taking their meals. Imperfect mastication is a prevailing cause of indigestion.
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What persons would be benefited by observing the preceding remarks? 307. Why should food be well masticated? What is the effect of "bolting down" food? 308. How should mastication be performed? Why?
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309. Food should be masticated and swallowed without drink. As the salivary glands supply fluid to moisten the dry food, the use of tea, coffee, water, or any other fluid, is not demanded by nature's laws while taking a meal. One objection to "washing down" the food with drink is, the aliment is moistened, not with the saliva, but with the drink. This tends to induce disease, not only in the salivary organs, by leaving them in a state of comparative inactivity, but in the stomach, by the deficiency of the salivary stimulus. Another is, large quantities of fluids, used as drinks, give undue distention to the stomach, and lessen the energy of the gastric juice by its dilution, thus retarding digestion. Again, drinks taken into the stomach must be removed by absorption before the digestion of other articles is commenced.
Observation. Were it customary not to place drinks on the table until the solid food is eaten, the evil arising from drinking too much at meals would be obviated. The horse is never known to leave his provender, nor the ox his blade of grass, to wash it down; but many persons, from habit rather than thirst, drink largely during meals.
310. The peculiar sensation in the mouth and fauces, called thirst, may not always arise from the demand for fluids to increase the serum (water) of the blood, as in the desire for drink attendant on free perspiration, for then, pure water or some diluent drink is absolutely necessary; but it may be the result of fever, or local disease of the parts connected with the throat. In many instances, thirst may be allayed by chewing some hard substance, as a dry cracker. This excites a secretion from the salivary glands, which removes the disagreeable sensation. In thirst, attendant on a heated condition of the system, this practice affords relief, and is safe; while the practice of drinking large quantities of cold fluids, is unsafe, and should never be indulged.
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Why should all persons have ample time for eating? 309. Why are drinks not necessary while masticating food? Give the objections to "washing down" food. What observation relative to drink? 310. Does the sensation of thirst always arise from a real want of the system?
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311. Food or drink should not be taken when very hot. When food or drink is taken hot, the vessels of the mucous membrane of the gums, mouth, and stomach are unduly stimulated for a short time; and this is followed by reaction, attended by a loss of tone, and debility of these parts. This practice is a fruitful cause of spongy gums, decayed teeth, sore mouth, and indigestion.
312. Food or drink should not be taken very cold. If a considerable quantity of very cold food or liquid be taken immediately into the stomach, the health will be endangered, and the tone of the system will be impaired, from the sudden abstraction of heat from the coats of the stomach, and from surrounding organs, to impart warmth to the cold food or drink. This arrests the digestive process, and the food is retained in the stomach too long, and causes oppression and irritation. Consequently, food and drink that are moderately heated are best adapted to the natural condition of the digestive apparatus.
Observation. Food of an injurious quality, or taken in an improper manner, affects the inferior animals as well as man. The teeth of cows that are closely penned in cities, and are fed on distillery slops, or the unhealthy slops and remnants of kitchens, decay and fall out in about two years. Can the milk of such diseased animals be healthy—the proper nourishment for children?
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Give instances when it does and when it does not. 311. Why should not food or drink be taken hot? 312. Why should they not be taken cold? Show some of the effects of improper food upon the inferior animals.
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313. The CONDITION of the system should be regarded when food is taken. This is necessary, as the present and ulterior condition of the digestive apparatus is strongly influenced by the state of the other organs of the system.
314. Food should not be taken immediately after severe exertion, either of the body or mind. For all organs in action require and receive more blood and nervous fluid, than when at rest. This is true of the brain, muscles, and vocal organs, when they have been actively exercised. The increased amount of fluid, both sanguineous and nervous, supplied to any organ during extra functional action, is abstracted from other parts of the system. This enfeebles and prostrates the parts that supply the blood and nervous fluid to the active organ. Again, when any organ has been in vigorous action for a few hours, some time will elapse before the increased action of the arteries and nerves abates, and a due supply of fluids is transmitted to other organs, or an equilibrium of action in the system is reestablished.
315. Thus food should not be taken immediately after severe mental labor, protracted speaking, continued singing, or laborious manual toil; as the digestive organs will be in a state of comparative debility, and consequently unfit to digest food. From thirty to sixty minutes should elapse, after the cessation of severe employment, before food is taken. This time may be spent in cheerful amusement or social conversation.
Observation. The practice of students and accountants going immediately from severe mental labor to their meals, is a pernicious one, and a fruitful cause of indigestion and mental debility. The custom of farmers and mechanics hurrying from their toil to the dinner-table, does much to cause dyspepsia and debility among these classes in community.
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313. Should the condition of the system be regarded in taking food? 314. When should food not be taken? Why? What is the result when an organ has been in vigorous action? 315. After the cessation of severe toil, how much time should expire before eating? What is one cause of indigestion among students and accountants?
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316. Severe mental or manual toil should not be entered upon immediately after eating. As there is an increased amount of blood and nervous fluid supplied to the stomach and alimentary canal during the digestion of food, a deficiency exists in other organs. This is evinced by a slight paleness of the skin, and a disinclination to active thought and exercise. Under such circumstances, if either the mind, vocal organs, or muscles are called into energetic action, there will be an abstraction of the necessary amount of blood and nervous fluid from the stomach, and the process of digestion will be arrested. This will not only cause disease of the digestive organs, but chyle will not be formed, to nourish the system.
Illustration. An English gentleman fed two dogs upon similar articles of food. He permitted one to remain quiet in a dark room; the other he sent in pursuit of game. At the expiration of one hour, he had both killed. The stomach of the dog that had remained quiet was nearly empty. The food had been properly changed and carried forward into the alimentary canal. In the stomach of the dog that had used his muscles in chasing game, the aliment remained nearly unaltered.
317. The same principle may be applied to the action of the organs of man. If his mind or muscles act intensely soon after eating, the stomach will not be sufficiently stimulated by blood and nervous fluid to change the food in a suitable period. The Spanish practice of having a "siesta," or sleep after dinner, is far better than the custom of the Anglo-Saxon race, who hurry from their meals to the field, shop, or study, in order to save time, which, in too many instances, is lost by a sense of oppression and suffering which soon follows.
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316. Why should not severe manual or mental exertion be made immediately after eating? State the illustration. 317. May this principle be applied to the action of the human stomach? What is said of the Spanish custom of resting after dinner?
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318. In some instances of good health, the infringement of this organic law may seem to pass with impunity, but Nature, though lenient, sooner or later asserts her claims. The practice of the Spaniard may be improved by indulging, for an hour before resuming toil, in moderate exercise of the muscular system, conjoined with agreeable conversation and a hearty laugh, as this facilitates digestion, and tends to "shake the cobwebs from the brain."
Observation. No judicious teamster drives his animals as soon as they have swallowed their food, but gives them a period for repose, so that their food may be digested, and their systems invigorated. In this way, he secures the greatest amount of labor from his team.
319. The mind exerts an influence upon the digestive process. This is clearly exhibited, when an individual receives intelligence of the loss of a friend or of property. He may at the time be sitting before a plentiful board, with a keen appetite; but the unexpected news destroys it, because the excited brain withholds its stimulus. This shows the propriety of avoiding absorbing topics of thought at meals, as labored discussions and matters of business; but substitute cheerful and light conversation, enlivening wit, humor, the social intercourse of family and friends; these keep the brain in action, but not in toil. Under such circumstances, the blood and nervous fluid flow freely, the work of digestion is readily commenced, and easily carried on.
320. Indigestion arising from a prostration of the nervous system, should be treated with great care. The food should be simple, nutritious, moderate in quantity, and taken at regular periods. Large quantities of stimulating food, frequently taken, serve to increase the nervous prostration. Those afflicted should exercise in the open air, and engage in social conversation, that the brain may be excited to a natural or healthy action, in order that it may impart to the digestive organs the necessary stimulation.
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Of the Anglo-Saxon race? 318. How can the Spanish custom be improved? 319. How is the influence of the mind on the digestive process exhibited? What does it show the necessity of avoiding? 320. How should indigestion arising from nervous prostration be treated?
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321. Persons should abstain from eating, at least three hours before retiring for sleep. It is no unusual occurrence, for those persons who have eaten heartily immediately before retiring to sleep, to have unpleasant dreams, or to be aroused from their unquiet slumber by colic pains. In such instances, the brain becomes partially dormant, and does not impart to the digestive organs the requisite amount of nervous influence. The nervous stimulus being deficient, the unchanged food remains in the stomach, causing irritation of this organ.
Illustration. A healthy farmer, who was in the habit of eating one fourth of a mince pie immediately before going to bed, became annoyed with unpleasant dreams, and, among the varied images of his fancy, he saw that of his deceased father. Becoming alarmed, he consulted a physician, who, after a patient hearing of the case, gravely advised him to eat half of a mince pie, assuring him that he would then see his grandfather.
322. When the general system and digestive organs are enfeebled, mild, unstimulating food, in small quantities, should be given. In the instance of a shipwrecked and famished mariner, or a patient recovering from disease, but a small quantity of nourishment should be given at a time. The reason for this, is, that when the stomach is weakened from want of nourishment, it is as unfitted for a long period of action in digesting food, as the muscles are, under like circumstances, for walking. Consequently, knowledge and prudence should direct the administration of food under these circumstances. The popular adage, that "food never does harm when there is a desire for it," is untrue, and, if practically adopted, may be injurious and destructive to life.
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321. What is the effect of eating immediately before retiring for sleep? How is this illustrated in the case of a healthy farmer? 322. How should the food be given when both the digestive organs and general system are debilitated? Give the reason.
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Observation. Liquids are rapidly removed from the stomach by absorption. Hence, in cases of great prostration, when it is desirable to introduce nutriment into the system, without delay, the animal and vegetable broths are a desirable and convenient form of supplying aliment.
323. The condition of the skin exercises an important influence on the digestive apparatus. Let free perspiration be checked, either from uncleanliness or from chills, and it will diminish the functional action of the stomach and its associated organs. This is one of the fruitful causes of the "liver and stomach complaints" among the half-clothed and filthy population of the crowded cities and villages of our country. Attention to clothing and bathing would likewise prevent many of the diseases of the alimentary canal, called "season complaints," particularly among children.
324. Restricting the movements of the ribs and diaphragm impairs digestion. At each full inspiration, the ribs are elevated, and the central portion of the diaphragm is depressed, from one to two inches. This depression is accompanied by a relaxation of the anterior abdominal walls. At each act of expiration, the relaxed abdominal muscles contract, the ribs are depressed, the diaphragm relaxes, and its central parts ascend. These movements of the midriff cause the elevation and depression of the stomach, liver, and other abdominal organs, which is a natural stimulus of these parts.
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In cases of great prostration, what is recommended? 323. How is the influence that the skin exercises on the digestive organs illustrated? 324. What effect on the digestive process has the restriction of the ribs and diaphragm?
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325. It is noted of individuals who restrain the free movements of the abdominal muscles by tight dresses, that the tone and vigor of the digestive organs are diminished. The restricted waist will not admit of a full and deep inspiration and so essential is this to health, that abuse in this respect soon enfeebles and destroys the functions of the system.
326. Pure air is necessary to give a keen appetite and vigorous digestion. The digestive organs not only need the stimulus of blood, but they absolutely need the influence of pure blood, which cannot exist in the system, except when we breathe a pure air. From this we learn why those persons who sleep in small, ill ventilated rooms, have little or no appetite in the morning, and why the mouth and throat are so dry and disagreeable. The effect of impure blood, in diminishing the desire for food, and enfeebling the digestive organs, is well illustrated by the following incidents.
Illustrations. 1st. Dr. Reid, in his work on "Ventilation of Rooms," relates that an innkeeper in London, when he provided a public dinner, always spread his tables in an under-ground room, with low walls, where the air was confined and impure. He assigned as a reason for so doing, that his guests consumed only one third as much food and wine, as if the tables were laid in the open air.
2d. A manufacturer stated before a committee of the British Parliament, that he had removed an arrangement for ventilating his mill, because he noticed that his men ate much more after his mill was ventilated, than previous to admitting fresh air into the rooms, and that he could not afford to have them breathe pure air.
Observation. Many of the cases of indigestion among clergymen, seamstresses, school teachers, sedentary mechanics, and factory operatives, are produced by breathing the impure air of the rooms they occupy. These cases can be prevented, as well as cured, by proper attention to ventilation.
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325. What is observed of those individuals that restrict the movements of the abdominal muscles? 326. Why is pure air necessary to vigorous digestion? Give illustration 1st. Illustration 2d. What is one cause of indigestion among the sedentary class in community?
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327. The position of a person, in standing or sitting, exerts an influence upon the digestive organs. If a person lean, or stoop forward, the distance between the pelvic bones and the diaphragm is diminished. This prevents the depression of the diaphragm, while the stomach, liver, pancreas, and other abdominal organs, suffer compression, which induces many severe diseases of these organs. As healthy and well-developed muscles keep the spinal column in an erect position, which conduces to the health of the organs of digestion, the child should be taught to avoid all positions but the erect, while studying or walking. This position, combined with unrestricted waists, will do much to remove the now prevalent disease, dyspepsia.
328. Whatever kind of aliment is taken, it is separated into nutriment and residuum; the former of which is conveyed, through the medium of the circulation, to all organs of the system, and the latter, if not expelled, accumulates, causing headache and dizziness, with a general uneasiness; and, if allowed to continue, it lays the foundation of a long period of suffering and disease. For the preservation of health, it is necessary that there should be a daily evacuation of the residual matter.
Observation. In chronic diseases of the digestive organs, very frequently, there is an inactive, or costive condition of the alimentary canal. This may be removed in many cases, and relieved in all instances, by friction over the abdominal organs, and by making an effort at some stated period each day, (evening is best,) to evacuate the residuum. In acute diseases, as fever, regard should be given to regularity in relieving the intestines of residuum. Attention to this suggestion will in many instances obviate the necessity of cathartic medicine.
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327. Why does the position of a person affect digestion? 328. Into what are different kinds of aliment separated?
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329. We would add, for the benefit of those afflicted with hemorrhoids, or piles, that the best time for evacuating the intestinal canal would be immediately before retiring for the night. During the night, while recumbent, the protruding parts return to their proper place, and the surrounding organs acquire increased tone to retain them. The same observance will do much to prevent such prostrating diseases.[12]
[12] The urinary organs, as well as the intestinal canal, should be frequently and regularly evacuated. Some most distressing and frequently incurable complaints are caused by false customs and false delicacy in this particular. Teachers should be particularly careful, and regard this suggestion in reference to young pupils.
330. To recapitulate: digestion is most perfect when the action of the cutaneous vessels is energetic; the brain and vocal organs moderately stimulated by animated conversation; the blood well purified; the muscular system duly exercised; the food of an appropriate quality, taken in proper quantities, at regular periods, and also properly masticated.
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330. Give the summary when digestion is most perfect.
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CHAPTER VXII.
THE CIRCULATORY ORGANS.
331. The ultimate object of the food and drink introduced into the body, is to furnish material to promote the growth and repair the waste of the organs of the system. The formation of chyle (the nutrient portion of the food) has been traced through the digestive process, and its transfer into the vein at the lower part of the neck, from which it is conveyed to the heart; and, finally, in the lungs it assimilates to the character of blood.
332. The BLOOD, after standing a short time, when drawn from its vessels, separates into se'rum, (a watery fluid,) and co-ag'u-lum, (clot.) This fluid is distributed to every part of the system. There is no part so minute that it does not receive blood. The organs by which this distribution is effected are so connected that there is properly neither beginning nor end; but as it respects their functions, they are connected in a complete circle. From this circumstance, they are called the Circulatory Organs.
ANATOMY OF THE CIRCULATORY ORGANS.
333. The CIRCULATORY ORGANS are the Heart, Ar'te-ries, Veins, and Cap'il-la-ries.
334. The HEART is placed obliquely, in the left cavity of the chest, between the right and left lung. Its general form is that of an inverted cone, the base of which is directed upward and backward, toward the right shoulder, while its apex points forward to the left side, about three inches from the sternum to the space between the fifth and sixth ribs. Its under side rests upon the tendinous portion of the diaphragm. The heart is surrounded by a sac, called the per-i-car'di-um, (heart-case.) The interior surface of this membrane secretes a watery fluid, that lubricates the exterior of the heart, and obviates friction between it and the pericardium.
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331. what is the ultimate object of the food? 332. Of what is the blood composed? What is said of the distribution of the blood? 333. Name the circulatory organs. 334-351. Give the anatomy of the circulatory organs. 334. Describe the heart.
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through which the blood passes to and from the heart.]
[13] All vessels that carry blood to the heart, are called veins. All vessels that carry blood from the heart, are called arteries.
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With what is it surrounded? What is its use? How much fluid does this membrane contain when healthy?
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Observation. In health, there is usually about a tea-spoonful of fluid in the pericardium. When these parts are diseased, it may be thrown out more abundantly, and sometimes amounts to several ounces, producing a disease called dropsy of the heart. But all the unpleasant sensations in the region of the heart are not caused by an increased amount of fluid in the pericardium, as this disease is not of frequent occurrence.
335. The heart is composed of muscular fibres, that traverse it in different directions, some longitudinally, but most of them in a spiral direction. The human heart is a double organ, or it has two sides, called the right and the left. The compartments of the two sides are separated by a muscular sep'tum, or partition. Again, each side of the heart is divided into two parts, called the Au'ri-cle (deaf ear) and the Ven'tri-cle.
336. The AURICLES differ in muscularity from the ventricles. Their walls are thinner, and of a bluish color. These cavities are a kind of reservoir, designed to contain the blood arriving by the veins.
337. The VENTRICLES not only have their walls thicker than the auricles, but they differ in their internal structure. From the interior of these cavities arise fleshy columns, called co-lum'nae car'ne-ae. The walls of the left ventricle are thicker and stronger than those of the right.
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335. Of what is the heart composed? Give its divisions. 336. Describe the auricles. 337. Describe the ventricles.
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338. The cavities in the right side of the heart are triangular in shape; those of the left, oval. Each cavity will contain about two ounces of blood. Between the auricle and ventricle in the right side of the heart, there are three folds, or doublings, of thin, triangular membrane, called the tri-cus'pid valves. Between the auricle and ventricle in the left side, there are two valves, called the mi'tral. There are seen passing from the floating edge of these valves to the columnae carneae, small white cords, called chor'dae ten'di-nae, which prevent the floating edge of the valve from being carried into the auricle.
339. The right ventricle of the heart gives rise to the Pul'mo-na-ry artery; the left ventricle, to a large artery called the A-ort'a. At the commencement of each of these arteries there are three folds of membrane, and from their shape, they are called sem-i-lu'nar valves.
340. The heart is supplied with arteries and veins, which ramify between its muscular fibres, through which its nutrient blood passes. It has, likewise, a few lymphatics, and many small nervous filaments from the sympathetic system of nerves. This organ, in its natural state, exhibits but slight indications of sensibility, and although nearly destitute of the sensation of touch, it is yet, however, instantly affected by every painful bodily excitement, or strong mental emotions.
Observation. To obtain a clear idea of the heart and its valves, it is recommended to examine this part of an ox or calf. In order that each ventricle be opened without mutilating the fleshy columns, tendinous cords, and valves, cut on each side of the septum parallel to it. This may be easily found between the ventricles, as they differ in thickness.
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338. How do the cavities in the heart differ? What is found between the auricle and ventricle in the right side of the heart? How many valves in the left side, and their names? Where are the tendinous cords, and what is their use? 339. What vessels proceed from the ventricles? What is said of their valves? 340. With what is the heart supplied? What is said of its sensibility? How can an idea of the structure of the heart be obtained?
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341. The ARTERIES are the cylindrical tubes that convey the blood from the heart to every part of the system. They are dense in structure, and preserve, for the most part, the cylindrical form, when emptied of their blood, which is their condition after death.
342. The arteries are composed of three coats. The external, or cellular coat, is firm and strong; the middle, or fibrous coat, is composed of yellowish fibres. This coat is elastic, fragile, and thicker than the external coat. Its elasticity enables the vessel to accommodate itself to the quantity of blood it may contain. The internal coat is a thin, serous membrane, which lines the interior of the artery, and gives it the smooth polish which that surface presents. It is continuous with the lining membrane of the heart.
343. Communications between arteries are free and numerous. They increase in frequency with diminution in the size of the branches, so that through the medium of the minute ramifications, the entire body may be considered as one circle of inosculation. The arteries, in their distribution through the body, are enclosed in a loose, cellular investment, called a sheath, which separates them from the surrounding tissues.
344. The PULMONARY ARTERY commences in front of the origin of the aorta. It ascends obliquely to the under surface of the arch of the aorta, where it divides into two branches, one of which passes to the right, the other to the left lung. These divide and subdivide in the structure of the lungs, and terminate in the capillary vessels, which form a net-work around the air-cells, and become continuous with the minute branches of the pulmonary veins. This artery conveys the impure blood to the lungs, and, with its corresponding veins, establishes the lesser, or pulmonic circulation.
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341. What are arteries? 342. Give their structure. 343. What is said of the communications between the arteries? In their distribution, how are they separated from the surrounding tissues? 344. Describe the pulmonary artery.
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345. The AORTA proceeds from the left ventricle of the heart, and contains the pure, or nutrient blood. This trunk gives off branches, which divide and subdivide to their ultimate ramifications, constituting the great arterial tree which pervades, by its minute subdivisions, every part of the animal frame. This great artery and its divisions, with their returning veins, constitute the greater, or systemic circulation.
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What does this artery and its corresponding veins establish? Explain fig. 69. 345. Describe the aorta. What do this artery and its corresponding veins constitute?
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346. The VEINS are the vessels which return the blood to the auricles of the heart, after it has been circulated by the arteries through the various tissues of the body. They are thinner and more delicate in structure than the arteries, so that when emptied of their blood, they become flattened and collapsed. The veins commence by minute radicles in the capillaries, which are every where distributed through the textures of the body, and coalesce to constitute larger and larger branches, till they terminate in the large trunks which convey the dark-colored blood directly to the heart. In diameter they are much larger than the arteries, and, like those vessels, their combined area would constitute an imaginary cone, the apex of which is placed at the heart, and the base at the surface of the body.
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What does fig. 70 represent? 346. What are the veins?
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347. The communications between the veins are more frequent than between the arteries, and take place between the larger as well as among the smaller vessels. The office of these inosculations is very apparent, as tending to obviate the obstructions to which the veins are peculiarly liable, from the thinness of their coats, and from inability to overcome great impediments by the force of their current. These tubes, as well as the arteries, are supplied with nutrient vessels, and it is to be presumed that nervous filaments from the sympathetic nerves are distributed to their coats.
348. The external, or cellular coat of the veins, is dense and firm, resembling the cellular tunic of the arteries. The middle coat is fibrous, like that of the arteries, but extremely thin. The internal coat is serous, and also similar to that of the arteries. It is continuous with the lining membrane of the heart at one extremity, and with the lining membrane of the capillaries at the other.
349. At certain intervals, the internal coat forms folds, or duplicatures, which constitute valves. They are generally composed of two semilunar folds, one on each side of the vessel. The free extremity of the valvular folds is concave, and directed forward, so that while the current of blood sets toward the heart, they present no impediment to its free passage; but let the current become retrograde, and it is impeded by their distention. The valves are most numerous in the veins of the extremities, particularly the deeper veins situated between the muscles; but in some of the larger trunks, and also in some of the smaller veins, no valves exist.
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Where do they commence? 347. What is said of their communications? What is the apparent design of the inosculations of the veins? What vessels are distributed to the coats of the veins? 348. Give the structure of the coats of the veins. 349. How are the valves in the veins formed?
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What is their use? Where are they the most numerous?
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350. The CAPILLARIES constitute a microscopic net-work, and are so distributed through every part of the body as to render it impossible to introduce the smallest needle beneath the skin, without wounding several of these fine vessels. They are remarkable for the uniformity of diameter, and for the constant divisions and communications which take place between them.
351. The capillaries inosculate, on the one hand, with the terminal extremity of the arteries, and on the other, with the commencement of the veins. They establish the communication between the termination of the arteries and the beginning of the veins. The important operations of secretion and the conversion of the nutrient materials of the blood into bone, muscle, &c., are performed in these vessels.
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350. What do the capillaries constitute? For what are they remarkable? 351. What relation do they bear to the arteries and veins? What important operations are performed in these vessels? What is represented by fig. 72? By fig. 73?
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CHAPTER XVIII.
PHYSIOLOGY OF THE CIRCULATORY ORGANS.
352. The walls of all the cavities of the heart are composed of muscular fibres, which are endowed with the property of contracting and relaxing, like the muscles of the extremities. The contraction and relaxation of the muscular tissue of the heart, produce a diminution and enlargement of both auricular and ventricular cavities. The auricles contract and dilate simultaneously, and so do the ventricles; yet the contraction and dilatation of the auricles do not alternate with the contraction and dilatation of the ventricles, as the dilatation of the one is not completed before the contraction of the other commences. The dilatation of the ventricles is termed the di-as'to-le of the heart; their contraction, its sys'to-le.
353. The ventricles contract quicker and more forcibly than the auricles, and they are three times longer in dilating than contracting. The walls of the right ventricle, being thinner than the left, are more distensible, and thus this cavity will contain a greater amount of blood. This arrangement adapts it to the venous system, which is more capacious than the arterial. The thicker and more powerful walls of the left ventricle adapt it to expel the blood to a greater distance.
354. The valves in the heart permit the blood to flow from the auricles to the ventricles, but prevent its reflowing. The valves at the commencement of the aorta and pulmonary artery, permit the blood to flow from the ventricles into these vessels, but prevent its returning.
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352-366. Give the physiology of the circulatory organs. 352. What do the contraction and relaxation of the muscular walls of the heart produce? How do the auricles and ventricles contract and dilate? 353. What is said of the contraction and dilatation of the ventricles in the heart? How is the right ventricle adapted to its function? How the left? 354. What is the use of the valves in the heart? Those of the aorta and pulmonary artery?
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355. The function of the different parts of the heart will be given, by aid of fig. 74. The blood passes from the right auricle (3) into the right ventricle, (5,) and the tricuspid valves (6) prevent its reflux; from the right ventricle the blood is forced into the pulmonary artery, (7,) through which it passes to the lungs. The semilunar valves (9) prevent this circulating fluid returning to the ventricle. The blood, while passing over the air-cells in the lungs, in the minute divisions of the pulmonary artery, is changed from a bluish color to a bright red. It is then returned to the left auricle of the heart by the pulmonary veins, (11, 11.)
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355. Describe the course of the blood from the right auricle in the heart to the lungs.
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Observation. If the blood is not changed in the lungs, it will not flow to the pulmonary veins. This phenomenon is seen in instances of death from drowning, strangling, carbonic acid, &c. The same is true, but in a less degree, of individuals whose apparel is tight, as well as of those who breathe impure air, or have diseased lungs.
356. The left auricle, (12,) by its contraction, forces the blood into the left ventricle, (14.) The mitral valves (15) prevent its reflowing. From the left ventricle the blood is forced into the aorta, (16,) through which, and its subdivisions, it is distributed to every part of the system. The semilunar valves (17) prevent its returning. |
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